Plural Anode Time-of-Flight Sensor for Moving Object Detection
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Solution Overview
Problem
Time-of-flight (TOF) cameras face challenges in accurately collecting distance data from moving objects due to mismatches in image and normalization light acquisition times, and short gated time periods leading to errors in distance estimation.
Innovation Solution
The implementation of light-sensitive pixels with an evacuated cavity and a photoelectric cathode, along with multiple anodes for electron collection, allows for reduced delay times between gating periods, enhancing the accuracy of distance estimation by improving light collection efficiency and reducing shot noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional light-sensitive pixels are used with standard gating periods, then device complexity is reduced, but delay times between gating periods increase causing inaccuracies in distance estimation for moving objects
Solution Approach 1:
The pixel is divided into multiple independent anodes (first anode, second anode, third anode) that can be independently controlled and activated. Each anode corresponds to a specific gating period, allowing sequential activation without cross-interference. This segmentation enables precise timing control for moving object detection while maintaining measurement accuracy.
Solution Approach 2:
The patent implements dynamic switching between multiple anodes based on the timing requirements of different gating periods. The system dynamically activates the appropriate anode (first, second, or third) depending on which gating period is currently active, enabling adaptability to moving objects while reducing delay times between measurements.
2Measurement precision
If single anode configuration is used, then device complexity is minimized, but light collection efficiency decreases leading to increased shot noise
Solution Approach 1:
The light collection function is segmented across three independent anodes instead of using a single anode. Each anode can be independently activated during its corresponding gating period, allowing the system to collect light from moving objects at different positions without signal interference, thereby improving measurement precision.
Solution Approach 2:
The evacuated cavity acts as an intermediary space that enables electrons generated at the photocathode to be efficiently collected by the respective anodes. The vacuum environment ensures that electrons travel without collision, improving light collection efficiency and reducing shot noise while maintaining a manageable device structure.
3Measurement precision
If longer gating periods are used, then light collection efficiency improves, but temporal resolution decreases causing errors in distance estimation for moving objects
Solution Approach 1:
The measurement process is segmented into three distinct gating periods, each associated with a specific anode. This segmentation allows the system to perform multiple rapid measurements in sequence, reducing the effective delay time between measurements while maintaining sufficient light collection during each gated period.
Solution Approach 2:
The system maintains continuous measurement capability by sequentially activating different anodes during different gating periods. The transition between anodes is designed to be rapid and seamless, ensuring that the useful action of distance measurement continues without significant interruption or delay, thereby improving temporal resolution for moving objects.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution increases the accuracy of distance data collection by minimizing delays and errors, enabling more precise distance estimation in TOF cameras, especially for moving objects.
Implementation Method 1
a photoelectric cathode for generating electrons responsive to light incident on the light-sensitive pixel
Implementation Method 2
an evacuated cavity formed in an insulating substrate. The light-sensitive pixel further includes a photoelectric cathode for generating electrons responsive to light incident on the light-sensitive pixel. The photoelectric cathode is located in the evacuated cavity
Data Source
AI summary
A time of flight (TOF) camera comprises a light source for illuminating an object with light and a plurality of light-sensitive pixels for collecting return image light reflected by the object. Further, each light-sensitive pixel of the TOF camera may comprise a photoelectric cathode for generating electrons responsive to return image light incident on the pixel and a plurality of anodes for collecting electrons generated at the photoelectric cathode.